Power operated treatment chair

ABSTRACT

The chair has an occupant supporting assembly including a seat rest and a relatively adjustable or tiltable back rest with associated power means for tilting the back rest, for raising and lowering the occupant support assembly, and for shifting the same forwardly and rearwardly in a rectilinear path relative to a supporting base of the chair without necessarily changing the relationship between and the attitude of the back rest and the seat rest.

United States Patent 11 1 Leffler Apr. 16, 1974 [54] POWER OPERATED TREATMENT CHAIR 3,330,523 7/1967 Nichols 297/330 x 3,578,379 5/1971 T l 297/330 X [75] Invent: Dennis Frank Lem, Charlotte" 3,596,982 8/1971 297/330 N.C. 1 3,698,673 10/1972 Olsen 297/330 [73] Assigneez Peltron & Crane Company, 3,719,391 3/1973 Nerl 297/330 Charlotte, NC. Primary Examiner-Paul R. Gilliam [22] Filed: May 30, 1972 [21] Appl. No.: 257,743 [57] ABSTRACT The chair has an occupant supporting assembly in- 52 U.S. c1 297/330, 297/71, 297/347 eluding a Seat rest and a relatively adjustable 9r tilt- 51] Int. (:1 A6lg 15/00, A47c 1/04 able back rest with associated Power means for tilting 58] Field of Search 297/330, 337, 339, 340, the back rest, for raising and lowering the occupant 297/341, 347, 329, 71, 80, 70, 348; 24 /421 support assembly, and for shifting the same forwardly and rearwardly in a rectilinear path relative to a sup- [5 References Cited porting base of the chair without necessarily changing UNITED STATESPATENTS the relationship between and the attitude of the back rest and the seat rest. 2,839,124 6/1958 Desmond et a1 297/330 X 3,025,108 3/1962 Teaque 297/330 x 12 Claims, 21 Drawing Figures 1 PATENTEUAPR 161974 3,804L460 sum 02 0? w PATENTEDAPMB m4 saw on a? 10 PATENTEB APR 1 6 I974 mam ms 0? w QV AA 3w Q NM w MTENTEMPR 16 m4 sum as HF 10 PATENTEWMMM 3.804.460

sum 10 0F 10 POWER OPERATED TREATMENT CHAIR This invention relates to adjustable chairs, and more particularly, to an improved treatment chair ideally suited for use by dentists, surgeons, ophthalmologists, chiropractors, beauticians, and the like.

Generally, treatment chairs such as used in the modern practice of dentistry include an occupant supporting assembly comprising a seat rest and an angularly adjustable or tiltable back rest on which a head rest is adjustably supported. In some instances, a leg rest or thigh rest is formed as an integral part of the seat rest, and in other instances, the leg rest is angularly adjustable or tiltable relative to the seat rest. Various forms of mechanisms have been proposed heretofore for angularly adjusting the seat rest, the back rest and the leg rest relative to each other and for raising and lowering the latter occupant supporting components relative to the supporting base of the chair.

It is well known that it is highly desirable for a dentist,- oral surgeon, ophthalmologist or beautician to be able to work within a relatively small area, usually quite close to particular operatory equipment, while operating upon a patient or other occupant of the chair, notwithstanding the fact that the operator or his assistant must be able to quickly change the angular position and level of the patients trunk and head while operating on the patient. Therefore, in order that the patients head may occupy a position close to the operator without reguiring that the operator move from place to place at such times that the angular position of the back rest must be adjusted, it is desirable also for the operator to be able to quickly change the position of the entire occupant supportingassembly in a longitudinal or rectilinear direction; i.e., forwardly andrearwardly, with.or without changing the relationship between and the attitude of the seat rest, back rest and' leg rest. l

Although a treatment chair has been proposed heretofore having a seat rest movable vertically and forwardly and rearwardly on its stationary supporting structure, as far as is known, the same power mechanism which effected forward and rearward movement of the seat rest also necessarily effected the tilting or angular adjustment of the back rest. Consequently, the angular position of the back rest could not be changed by a power means operating independently of another power means which effected rectilinear movement of the seat rest.

It is therefore an object of this invention to provide an improved treatment chair having highly efficient, stable and compact powered mechanism and controls for operating certain relatively movable components of the chair, either individually or collectively, to shift the occupant supporting assembly forwardly and rearwardly, to raise and lower the same, and to tilt or adjust the angular positions of the seat rest, back rest and leg rest components of the chair relative to each other.

Another object is to provide a treatment chair of the character describedwherein the powered mechanism includes power means for shifting the occupant supporting assembly forwardly and rearwardly, other power means for raising and lowering the seat rest component and for tilting the seat rest. back rest and leg rest components relative to each other, and control means connected to the power means for automatically moving the seat rest. back rest, and leg rest components to predetermined treatment positions relative to each other and relative to the stationary supporting base of the chair to locate a patient or customer on the chair in a supine position at a predetermined level for being operated upon by an operator in the event that any of the components do not already occupy the predetermined treatment positions.

Still another object of the invention is to provide a treatment chair of the character last described wherein the control means also is operable to automatically move the aforementioned components to predetermined exit positions relative to each other and relative to the base to facilitate a person leaving or entering onto the occupant supporting assembly of the chair.

It is another object of this invention to provide individual manually operable switch members for controlling (a) the rectilinear shifting of the occupant supporting assembly of the chair, including the seat rest, back rest, and leg rest components thereof, (b) the raising and lowering of the occupant supporting assembly, and (c) the angular adjusting of the seat rest, back rest, and leg rest components relative to each other, and wherein each of the individual switch members is operable to abort or override the aforementioned automatic movements of the components to either of the treatment or exit positions so as to stop further movements thereof in the event that the operator desires to stop such components in predetermined intermediate positions or in the event such further movements :might be considered mentally or physically hazardous to the patient.

Some of the objects and advantages of the invention having been stated, others will appear when taken in connection with the accompanying drawings, in which FIGS. 1 and 2 are right-hand side elevations of a preferred embodiment of the treatment chair of this invention with the components of the occupant supporting assembly thereof occupying respective exit and treatment positions;

' FIG. 3 is a schematic view showing various relative positions occupied by the back rest, seat rest, and leg rest components of thechair in the course of automatic operation thereof between the exit and'treatment positions;

FIG. 4 is an enlarged rear elevation of the chair looking at the left-hand side of the FIG. 2, but omitting the chair cushions, the leg rest and the rear wall means of an elevator enclosure;

FIG. 5 is a further enlarged fragmentary rear elevation of the upper central portion of FIG. 4, but with the back rest occupying a more erect or steeply inclined position than that shown in FIGS. 2 and 4, and being taken looking substantially along line 5-5 in FIG. 1;

FIG. 6 is an enlarged front elevation of the chair looking substantially in the direction of the arrow indicated at 6 in FIG. 1, omitting the front wall means of the elevator enclosure, the back rest, the leg rest and the seat cushion, and with other parts broken away for purposes of clarity;

FIG. 7 is an enlarged plan view of the chair as shown in FIG. 2, with portions broken away, and omitting the cushions of the occupant supporting assembly;

FIG. 8 is a longitudinal vertical sectional view taken substantially along line 8-8 in FIG. 7;

FIG. 9 is an enlarged, fragmentary, transverse vertical sectional view taken substantially along line 9--9 in FIG. 8;

FIG. 10 is a fragmentary longitudinal vertical sectional view taken substantially along line 10-40 in FIG. 7, but showing the components of the occupant supporting assembly occupying exit position, as in FIG.

FIG. 11 is an enlarged fragmentary transverse vertical sectional view taken substantially along line ll1 l in FIG. 10;

FIG. 12 is a partially exploded perspective view of the chair omitting its supporting base;

FIG. 13 is a schematic diagram of electrical circuitry embodying the novel control means of the invention;

FIG. 14 is an enlarged, partially exploded perspective view of a medial portion of the thrust beam 55 in the central portions of FIGS. 7 and 8 and showing certain electric switches in association with the thrust beam;

FIGS. 15 and 16 are further enlarged fragmentary views looking in the direction of the arrow 15 in FIG. 14;

FIGS. 17 and 18 are enlarged perspective views showing how the respective pairs of switches O51, OS2 and D51, D82 of FIG. 4 may be mounted on the elevator platform;

FIG. 19 is a sectional plan view taken substantially along line 19-19 in FIG. 18;

FIG. 20 is a partially exploded view similar to the lower portion of FIG. 12, but showing a modified drive means for shifting the main carriage relative to the elevator platform; and

FIG. 21 is a fragmentary detail of the modified drive means of FIG. 20.

GENERAL DESCRIPTION Referring more specifically to the drawings, the preferred embodiment of the improved treatment chair of this invention is best shown in FIGS. 1 and 2 and comprises an occupant supporting assembly 20 whose essential components include a seat rest 21, a back rest 22 and a leg rest 23 arranged in articulated relationship for relative angular movement by novel means to be later described. The occupant supporting assembly 20 is carried by carriage means comprising a main carraige 24 (FIGS. 4-12) mounted for longitudinal or rectilinear movement, forwardly and rearwardly, in a substantially straight and substantially horizontal path, on and relative to an elevator platform 25. Novel elevator means or lift means is provided for raising and lowering platform 25 in a substantially linear, vertical path independently of a traversing means for carriage 24 and independently of a means for adjusting the angular relationship between seat rest 21, back rest 22 and leg rest 23.

The elevator means for platform 25 is suitably secured to a stationary base 26. Base 26 may be of conventional or any other suitable construction facilitating angular adjustment of the elevator means and platform 25 about the median vertical axis of platform 25, if desired.

ELEVATOR MEANS The elevator means is in the form of a poweroperated parallelogram or lazy-tong linkage comprising two complementary sets of relatively expansible and contractible links 3l-34, 31a-34a (FIGS. 4, 6, 8, l and 12). The rear ends oflinks 31, 32 and 31a, 320 are pivotally connected in vertically spaced relationship to respective standards 35, 35a (FIGS. 8, and 12) suitably secured to stationary base 26. The rear ends of the pairs of links 33, 34 and 33a, 34a are pivotally connected, respectively, at points in vertically spaced relationshp and vertically aligned with the rear pivot points of links 31, 32 and 31a, 32a, to opposite sides of depending rear portions 25 of platform 25. The front ends of links 31, 33, 31a, 33a are pivotally mounted on a common pivot shaft 36 having the lower portions of a pair of upright links 37, 37a pivotally mounted thereon. The front portions of the respective pairs of links 32, 34 and 32a, 34a are pivotally interconnected and are also pivotally connected to the upper end portions of the respective upright links 37, 37a on the same axis. Relatively offset portions of the respective pairs of parallelogram links 31, 34 and 31a, 34a are pivotally connected to opposite ends of respective connecting links 40, 40a.

DRIVE FOR ELEVATOR MEANS A pivot shaft 41 (FIG. 8) is carried by and extends between front portions of the uppermost parallelogram links 34, 34a, forwardly of upright link 37, 37a, and has the upper forward portion of a hollow bracket 42 pivotally mounted thereon to which a reversible electric motor 43 is suitably secured. The output shaft of motor 43 has a gear 43a fixed thereon which meshes with a relatively larger gear 431; loosely mounted on a lead screw 43c whose upper portion is mounted for telescopic movementwithin and relative to hollow bracket 42.

Gear 4312 is suitably restrained from axial movement along lead screw 430 relative to hollow bracket 42 and has a ball nut 43d, of conventional or other suitable construction, suitably secured thereto and encircling lead screw 430. The lower rear portion of lead screw 43c is pivotally connected, as at 43e, to stationary base 26 (FIGS. 6, 8 and 12).

From the foregoing description, it is apparent that. upon motor 43 rotating ball nut 43a in one direction, ball nut 43d traverses upwardly along lead screw 43c to expand the parallelogram linkage thus causing bracket 42, motor 43 and the upper parallelogram links 34, 34a to move upwardly for elevating platform 25 in a substantially straight vertical path while maintaining the same in a substantially level attitude. Conversely, when motor 43 rotates ball nut 43a in the opposite or reverse direction, it traverses downwardly along lead screw 430 to contract the parallelogram linkage and lower the platform 25 in said substantially vertical straight path while maintaining the same in substantially level attitude.

Since the combined weight of the structure supported by links 31-34, 3la-34a and a person resting on the occupant supporting assembly may be up to 500 pounds or more in some instances, it is preferred that elevator motor 43 is equipped with a suitable brake means of any well-known type, such as a one-way brake, which will prevent elevator platform 25 from coasting downwardly whenever motor 43 is energized. Although electric motor 43, lead screw 43c and ball nut 43d constitute the preferred means for expanding and contracting linkages 31-34, 31a-34a, it is contemplated that fluid-operated means, such as a doubleacting cylinder assembly, may be used in place of motor 43, screw 43c and ball nut 43d. A suitable telescopic enclosure 44 is connected to the front, rear and opposing side edges of platfonn 25, extends downwardly therefrom, and is suitably connected to stationary base 26 for enclosing the elevator means therewithin.

MAIN CARRIAGE As best shown in FIGS. 7, 8, and 12, main carriage 24 is substantially longer than platform 25 and comprises a base plate 24a and a pair of laterally spaced elongate tracks or side rails 24b, 240 whose distal side portions are provided with respective longitudinal extending ribs 24d, 24e thereon. Ribs 24d, 24c are guided for longitudinal movement between respective longitudinally spaced pairs of guide rollers 25a, 25b journaled on and projecting inwardly from respective opposing upwardly extending side flanges 25c, 25d of platform 25.

SEAT CARRIAGE The carriage means also comprises an auxiliary carriage 50, which may be termed as a seat carriage. Seat carriage 50 is pivotally mounted adjacent its rear portion on main carriage 24 so that its front portion may be tilted to vary the angular position of seat rest 21 carried thereby, and so that seat carriage 50 and the occupant supporting assembly move to and fro with main carriage 24.

Seat carriage'50 is so constructed that it is nested between the main carriage side rails 24b, 24c whenever seat carriage 50 occupies substantially level position. Accordingly, seat carriage 50 comprises a pair of elon gate tracks or side rails 50a, 501) secured, in the desired laterally spaced substantially parallel relationship, to front and rear transverse frame members 21a, 21b of seat rest 21. Axially aligned, outwardly projecting stub shafts 50c, 50d (FIGS. 11 and 12) are carried by the rear portions of seat carriage side rails 50a, 50b and are suitably journaled in rear portions of the main carriage side rails 24b, 24c.

The proximal surfaces of seat carriage side rails 50a, 50!; are provided with respective longitudinally extending, inwardly facing, guide-ways or grooves 50e, 50f (FIG. 12) Grooves 50e, 50f are discontinuous, to the extent that the upper and lower portions of the side rails 50a, 50b defining the grooves 50e, 50f are cut away to provide elongate recesses 50g, 50h (FIG. 12) in the proximal medial portions of the respective seat carriage side rails 50a, 50b. Recesse s 50g, 5011 are provided to accommodate a pair of elongate tilting cams or ramps 51, 51a suitably adjustably secured to and projecting upwardly from plate member24a of main carriage 24. The proximal surfaces of tilting cams 51, 51a are spaced from eachother and have respective longitudinally extending cam grooves 51b therein. The cam grooves 51b are substantially straight and extend upwardly and forwardly at an angle so as to aid in the dual function of tilting seat rest 21 while tilting leg rest 23.

OCCUPANT SUPPORTING ASSEMBLY As heretofore described, the transverse frame 'members 21a, 21b, to which seat carriage side rails 50a, 50b are secured, are parts of seat rest 21. As best shown in FIGS. 7, 8, l0 and 12, the rear edge ofleg rest 23 is piv otally connected to an upper front transverse frame member 210 spaced above and rearwardly of transverse frame member 21a, asmeans of a hinge 23a. A suitable cushion 23b (FIGS. 1 and 2) may be mounted on and suitably attached to leg rest 23. Opposite ends of front transverse frame members 21a, 21c are suitably secured to opposing side frame members 21d, 21e, and opposite ends of rear transverse frame member 21b are suitably secured to a pair of upstanding pivot brackets 21f, 2lgwhich are, in turn, suitably secured to the rear portions of side frame members 21d, 21e of seat rest 21.

The major portion or body 22a of back rest 22 is of substantially lesser width than seat rest 21, and the lower portion of back rest 22 is provided with a pair of outwardly diverging and forwardly curved wing portions 22b, 22c on opposite sides thereof. Wing portions 22b, 220 are suitably pivotally connected, as at 22d, 222, to the respective brackets 21f, 21g of seat rest 21. The body 22a of back rest 22 is of built-up hollow construction forming a longitudinally extending passageway 22f (FIG. 7) for adjustably receiving therein the lower portion of a suitable head rest 52 (FIGS. 1 and 2) which may be of conventional or other construction and need not be described in detail.

Passageway 22f also accommodates electric wires extending from sets S, S of manual switches to other switches beneath the seat cushion 21h (FIGS. 1 and 2) of seat rest 21, as will be later described. Manual switch setsS, S are conveniently mounted on opposite side edges of back rest body 22a to be readily accessible to an operator and his assistant. A suitable back rest cushion 22g (FIGS. 1 and 2) may be secured to the front upper surface of back rest 22. Seat cushion 21h (FIGS. 1 and 2) rest upon transverse frame members 2112, 21c of seat rest 21 and may be suitably secured to one or the other or both frame members 2112, 21c.

TILT MECHANISM The mechanism for varying the angular relationship between seat rest 21, back rest 22 and leg rest 23, and relative to main carriage 24 and elevator platform 25, comprises a thrust means embodied in an elongate relatively narrow, longitudinally extending, composite thrust beam broadly designated at 55, details of which are best illustrated in FIGS. 7, 8 and 12. Thrust beam 55 is adapted to slide between the proximal surfaces of seat carriage side rails 50a, 50b and tilt cams 51, 51a. Thrust beam is preferably of a length approximately equal to that of seat carriage 50 and comprises a pair of spaced substantially parallel side bars 55a, 55b secured to opposite side edges of a toothed rack 55c spaced forwardly of the lateral plane of tilt earns 51, 51a and overlying the front portion of main carriage 24. The front ends of side bars 55a, 55b extend forwardly of rack 55c and have a roller 55d journaled therebetween on which a medial portion of leg rest 23 normally rests.

Suitable rollers or stub shafts 55e, 55f, 55g, 5511 (FIG. 12) are carried by and project laterally outwardly from the side bars 55a, 55b and are adapted to ride in the corresponding grooves 50e, 50f (FIGS. 11 and 12) of seat carriage side rails 50a, 50b. Rollers 55e, 55g are disposed forwardly of the lateral plane of tilt cams 51, 51a and adjacent rack 55c. Rollers 55f, 5511 are preferably axially aligned and positioned adjacent the rear ends of side bars 55a, 55b. Spaced forwardly from the rear ends of side bars 55a, 551), a distance roughly about one-third of the length of side bars 55a, 55b, is a follower 55i (FIGS. 7, 8, 9 and 12) which may extend through both side bars 55a, 55b with its opposite ends projecting outwardly from side bars 55a, 55b and engaging in the cam grooves 51b in the respective tilt earns 51, 51a. Thus, the upper surfaces of the lower walls of grooves 51b serve as a ramp supporting the medial portions of thrust beam 55 and seat carriage 50.

In order to connect back rest 22 to the rear end portion of thrust beam 55, the central lower portion of body 22a of back rest 22 is provided with a relatively narrow depending portion 22h to which the upper or rear end portion of a link 22: (FIGS. 1, 4, 5, 7, 8, l and 12) is pivotally connected, as at 22k. The depending portion 22h of back rest 22, and link 12i, are both of such width that they may pass freely between the rear portions of seat carriage side rails 50a, 50b. The front end of link 22i is pivotally mounted on a shaft 22m (FIGS. and 8) carried by and extending between the rear end portions of side bars 55a, 55b of thrust beam 55. Pivot shaft 22m preferably is axially aligned with the rear rollers 55f, 5511 (FIG. 12) and may be integral therewith.

From the foregoing description, it can be seen that, regardless of the position of main carriage 24 relative to elevator platform 25, whenever thrust beam 55 is moved forwardly relative to carriages 24, 50 and tilt cams 51, 51a, follower 551' causes thrust bar 55 to move upwardly and forwardly at an incline or angle relative to carriage 24 and platform 25 as in FIG. 8. In so doing, even though the rear portion of seat carriage 50 is pivotally mounted on main carriage 24, the rollers 55e-55h (FIG. 12) moving in engagement with the grooves 50e, 50fin the seat carriage side rails 50a, 50b, cause seat carriage 50 to tilt upwardly at its forward portion. Of course, this also causes thrust bar 55 to tilt upwardly in concert with seat carriage 50.

Thus, the front portion of seat rest 21 is tilted upwardly even though seat rest 21 may or may not be moving either forwardly or rearwardly at the time thrust beam 55 is being moved relative to main carriage 24. The extent to which seat rest 21 may be tilted relative to main carriage 24 is purposefully relatively small; e.g., in the range of about 3 to 7, between a substantially level position parallel to carriage 24 and its steepest tilted position.

As shown, however, the seat cushion 21h is positioned on frame members 211), 21c (FIGS. 8 and 10) so that its bottom is inclined upwardly and forwardly at an angle of about 10 to 12 relative to side frame members 21d, 210. Also, the upper surface of cushion 21h (FIGS. 1 and 2) may be parallel with its lower surface or it may be inclined upwardly and forwardly at an angle of about 5, for example. Thus, even when seat rest side frame members 21d, 212 occupy a level position, the upper surface of cushion 2111 may extend upwardly and forwardly at an angle of about 10 to 17, for example. relative to main carriage 24 and platform 25.

Since thrust beam 55 moves forwardly at the same time that its forward portion is being tilted upwardly with seat carriage 50, considerably greater angular movement is imparted to leg rest 23 than that being imparted to seat rest 21 during any forward movement of follower 551' along the tilt cam grooves 51b (FIGS. 8 and 12). In other words, the extent of angular movement of leg rest 23 while it is engaging roller 55d (FIG. 8) may be about 30 to 40, more or less.

Similarly, since the pivot points 22k, 22m of link 22i (FIG. 8) are offset subtantially from the pivotal axis 22d, 22e of back rest 22, forward movement of thrust beam 55 imparts considerably greater angular movement to back rest 22 than it does to seat rest 21. In fact, although back rest 22 may extend upwardly and rearwardly at an angle of about 15 with respect to a line perpendicular to elevator platform 25 when back rest 22 occupies a nearly vertical, erect or exit position (FIG. 1), the range of angular movement of back rest 22 effected by the movement of thrust beam 55, may be up to about 80.

DRIVE FOR TILT MECHANISM Selectively operable power means is provided for imparting forward and rearward movement to thrust beam 55 relative to main carriage 24, seat carriage and seat rest 21. To this end, a reversible electric motor 60, which may also be termed as a tilt motor, is suitably secured to a frame member 211' (FIGS. 7, 8 and 12) secured to and extending rearwardly from transverse frame member 21a. The drive shaft 60a of motor 60 extends laterally therefrom and is journaled in a pair of bearing blocks 60b (FIGS. 6, 7 and 12) carried by and projecting upwardly from the respective seat carriage side rails 50a, 5b. A pinion or gear 60c is suitably secured on shaft 60a between bearing blocks 60b and engages rack 550 (FIG. 8) of thrust beam 55.

It is apparent that rotation of pinion 60c in a forward or counterclockwise direction in FIGS. 8 and 12 imparts forward movement to thrust beam to tilt upwardly the front portion of seat rest 21 while swinging back rest 22 and leg rest 23 toward horizontal positions. Reverse or clockwise rotation of pinion 600 in FIGS. 8 and 12 returns the frame of seat rest 21 toward the substantially horizontal position while moving back rest 22 toward a substantially vertical or erect position and while permitting leg rest 23 to gravitate toward a vertical position. While it is preferred that electric motor is employed for imparting forward and rearward movement to thrust beam 25, it is contemplated that fluid-operated means, such as a double-acting cylinder assembly, may be used for this purpose.

CARRIAGE TRAVERSING MEANS Power means also is provided for shifting main carriage 24 forwardly and rearwardly relative to elevator platform 25 independently of vertical movement of elevator platform 25 and with or without longitudinal movement of thrust beam 55 relative to carriages 24, 50. Accordingly, a reversible electric motor 65, which also may be termed as a carriage motor (FIGS. 6, 7 and 12), is disposed in the space between right-hand side frame member 21d of seat rest 21 and the right-hand side flange 256 of elevator platform 25. The motors 43, 60, preferably are gear motors; i.e., motors whose gear boxes have worm and wormgear output portions, so that their output shafts will not rotate unless the respective motors are energized and so that their output shafts rotate at relatively slow speeds as compared to the speed of their rotors. Motor 65 is suitably secured to and depends from a support bracket 65a which extends inwardly over side flange 25c and has its innermost portion suitably secured to the right-hand side rail 24b of main carriage 24.

The axis of the drive shaft of carriage motor 65 extends in a direction transverse to the longitudinal direction of carriage 24 and has a pulley, drum or other suitable rotary member 65b fixed thereon. A taut doubleended cable 650 is wrapped firmly around pulley 65b,

and the front and rear ends of cable 65c are suitably secured to abutments 65d, 65e projecting outwardly from elevator platform 25. Thus, it is apparent that alternative rotation of pulley 65d in counterclockwise and clockwise directions in FIGS. and 12 imparts respective forward and rearward movements to carriage motor 65, bracket 65a, carriages 24, 50, and, thus, to the entire occupant supporting assembly 20, relative to platform 25;

Alternatively, the modified carriage traversing mechanism of FIGS. and 21 may be used, wherein it will be observed that drum 65b and cable 65c are replaced by a pinion 65b and a rack 65c. Rack 65c (FIGS. 20 and 21) is secured to one longitudinal side edge portion of elevator platform and pinion 65b is fixed on the output shaft of carriage motor 65. Although electric motor 65 constitutes the preferred embodiment of the means for shifting main carriage 2, and the occupant supporting assembly 20 carried thereby, to and fro relative to elevator platform 25, it is contemplated that fluid-operated means, such as a double-acting cylinder assembly, may be used for this purpose.

CONTROL MEANS The chair is provided with novel control means including manually operable switch means readily accessible to an operator on one side of the chair and an assistant on the other side of the chair for effecting operation of motors 43, 60, 65 either individually or in automatic predetermined timed or cyclical relationship to effect the respective substantially vertical, substantially horizontal and tilting operations of seat rest 21, back rest 22, and leg rest 23. To this end, the two sets of manually operable switches S, S are mounted in convenient positions on opposite side edge portions of the body 22a of back rest 22 (FIG..12), as heretofore stated, so as to be readily accessible to the operator and an assistant. Both sets of switches S, S are substantially identical and, therefore, only one of the sets of switches; i.e., set S, is shown in association with the electrical circuit in FIG. 13.

Each set of manually operable switches S, S includes an individual double-throw elevator switch A, an individual double-throw tilt switch B, an individual doublethrow carriage switch C, a normally open operate or treatment" switch D, and a normally open pushbutton exit" or entrance" switch E. Movable with and forming parts of the respective switches A, B, C are abort or override switches A, B, C. Thus, switches A, A; B, B and C, C are functionally double-pole switches. It is apparent that the manually operable switches of the set S may be arranged in parallel with the respective switches A E, A-C of the set S shown in FIG. 13. Alternatively, if desired, one exit switch and one treatment switch may be positioned on the top edge of back rest body 22a.

The electrical 'circuit includes eight electromagnetic relays CR1-CR8 suitably mounted on a relay panel 21 j (FIG. 7) attached to frame members 21c, 21c of seat rest 21. Relay CR1 serves as a treatment" cycle relay and controls five sets of contactslA-IE. Relay CR2 serves as an exit cycle relay and also controls five sets of contacts 2A-2E as shown in the left-hand portion of FIG. 13. In the right-hand portion of FIG. 13, it will be observed that relays CR3, CR4,CR5, CR6, CR7, CR8 control respective sets of contacts 3A-3C; 4A-4C; SA-SC; 6A-6C; 7A, 7C; and 8A-8C. Manually 10 operable switches A-E and relays CR1-CR8 preferably are arranged in a low-voltage circuit receiving its power from the secondary of a transformer 70 whose primary is connected to a relatively higher-voltage source of electrical energy by suitable lead conductors L, L. Although the low voltage circuit is shown arranged for alternating current, it is apparent that a direct current circuit may be used. a

The reversible electric motors 43, 60, 65 are provided with respective forward and reverse windings 43, 43"; 60"; 65" arranged in a high-voltage circuit connected to lead conductors L, L.

A solid state relay R, such as a thyristor, is provided for each windingof motors 43, 60, 65. Each relay R is normally inactive but upon being energized by the closing of a respective one of the contact sets 3A, 4A, 5A, 6A, 7A, 8A in the low voltage circuit, the corresponding relay R conducts and current flows in the high volt age circuit to the corresponding motor winding. Thus, when normally open contact sets 3A-8A are closed, they establisha high voltage circuit through the respective relays R to the respective motor windings 43', 43", 60', 60", 65, 65".

Manually operable double-pole switches A, A, B, B and C, C respectively are preferably of the type known as three-position rocker switches normally biased to open position such that, upon being moved in either direction, they will automatically return to a neutral or open position. Generally, when switches A-C are moved upwardly in FIG. 13, they actuate or energize the respective relays CR4, CR6, CR7, and when switches A-C are moved downwardly, they actuate or energize the respective relays CR3, CR5, CR8. The function of abort switches A-C will be later described. Upon an operator momentarily closing the respective treatment and exit switches D, E, they normally will actuate or energize the respective relays CR1, CR2 to initiate respective automatic treatment and exit cycles in the operation of the chair. The low voltage circuit also includes limit switches LSl-LS6, directionaP range switches DSl-DS4, treatment or operate range switches 081-053, and a solid state relay 71, such as a thyristor or "Triac. Thyristor 71 is a part of the abort system, as will be later described.

I METHOD OF OPERATION The control means embodied in the electrical circuitry of FIG. 13 is devised to permit operation of the elevator means, the tilting means for the components of the occupant supporting assembly, and the carriage shifting means either individually or automatically in predetermined timed relationship. First, the individual operation effected by the manuallly operable rocker switches A-C will be described.

At the outset, it should be noted, that the abort switches A'-C have no useful function during individual operations of platform 25, carriage 24 and the tilting means for seat rest 21, back rest 22 and leg rest 23.

INDIVIDUAL OPERATION OF ELEVATOR MEANS Assuming that the elevator platform 25 occupies a position on a lower level than its uppermost position, the operator moves individual elevator switch A to an upper operative position to close a circuit across the secondary of transformer 70, through switch A, limit switch LS1, normally closed contact set 3C and through relay CR4 to change the state of contact sets 4A, 4B, 4C. Thus, Contact set 4A establishes a high voltage circuit to forward winding 43 of elevator motor 43 and causes elevator platform 25 to move upwardly in the manner heretofore described. The upward movement of elevator platform 25 continues either as long as the operator holds switch A in the upper operative position or until the upper parallelogram link 34 (FIG. has pivoted downwardly relative to platform 25 sufficiently to engage and open limit switch LS1. Limit switches LS1, LS2 are suitably secured to one side of the depending rear portions 25' of elevator platform 25. When limit switch LS1 is opened, it breaks the circuit to relay CR4 to return contact sets 4A-4C to their original or normal state 'and stop motor 43.

To lower elevator platform 25 when it occupies other than its lowermost position, the operator moves elevator switch A downwardly to a lower operative position to energize relay CR3 through limit switch LS2 and normally closed contact set 4C, thereby changing the state of contact sets 3A-3C. In so doing, contact set 3A causes current to flow through reverse winding 43" of elevator motor 43, thereby causing elevator platform 25 to move downwardly. Elevator platform 25 continues to move downwardly either as long as the operator holds elevator switch A in the lower operative position (FIG. 13) or until limit switch LS2 (FIG. 10) is engaged and opened by the parallelogram link 32. Link 32 then is in the course of upward pivotal movement relative to elevator platform 25, as is apparent by comparing the position of the parallelogram links 3la-34a in FIG. 8 with the position of the parallelogram links 31-34 in FIG. 10.

INDIVIDUAL OPERATION OF TILTING MEANS As heretofore described, during reclining or downward and rearward tilting movement of back rest 22, the seat rest 21 and leg rest 23 are tilted upwardly at their front portions relative to each other by forward movement of thrust beam 55 relative to main carriage 24. In order to recline back rest 22 when it occupies other than its lowermost position, individual manually operable tilt switch B is moved downwardly in FIG. 13 to a lower operative position to energize relay CR5 through tilt switch B, normally closed limit switch LS4 and normally closed contact set 6C, thereby changing the state of contact sets 5A5C. In so doing, normally open contact set 5A establishes energization of the forward winding 60 of tilt motor 60 to impart forward movement to thrust beam 55 (FIG. 8).

Forward movement of thrust beam 55 continues for as long as the operator holds tilt switch B in the lower operative position or until an abutment 55j (FIG. 14), projecting upwardly from side bar 55b of thrust beam 55, engages and opens limit switch LS4. In this regard, it will be observed in FIG. 14 that limit switch LS4, as well as switches LS3, DS3, D84 and 083, are mounted on a bracket 21k carried by the frame of seat rest 21 and are so positioned that switches LS4, DS3 overlie side bar 5511, switch LS3 overlies bar 55a, and switches DS4, 083 are disposed between and above side bars 55a. 55b of thrust beam 55. By referring to FIG. 13, it is apparent that the flow of current to relay CR5 is interrupted when normally closed limit switch LS4 is opened, thus returning contact sets 5A-5C to their normal state to interrupt the flow of current to winding 60 of tilt motor 60.

To incline back rest 22 upwardly and forwardly when it occupies other than its uppermost and forwardmost or most steeply inclined position (FIGS. 1 and 10), the operator moves individual tilt switch B to an upper operative position (FIG. 13) to energize relay CR6 through normally closed limit switch LS3 and normally closed contact set 5C, thus changing the state of contact sets 6A-6C. This closes normally open contact set 6A to establish a high voltage circuit to reverse winding 60 of tilt motor 60 and thereby impart rearward movement to thrust beam (FIG. 8). Such rearward movement continues until tilt switch B is released by the operator or until an abutment 55k, projecting upwardly from side bar 55a of thrust beam 55 (FIG. 14), engages and opens normally closed limit switch LS3, whichever occurs first.

It is apparent that, when switch LS3 is opened, the flow of current to relay CR6 is interrupted, returning contact sets 6A-6C to their normal state and interrupting the flow of current to winding of tilt motor 60 to thereby stop further tilting of seat rest 21, back rest 22 and leg rest 23.

INDIVIDUAL OPERATION OF CARRIAGE TRAVERSING MEANS To shift carriage 24 forwardly and rearwardly other than during automatic cycling of motors 43, 60, 65, individual carriage switch C is moved upwardly (FIG. 13) to upper operative position to effect forward movement of carriage 24 if it does not already occupy its forwardmost position. To this end, manual movement of switch C to upper operative position energizes relay CR7 through limit switch LS6 and normally closed contact set 8C, thereby changing the state of contact sets 7A, 7C. This closes contact set 7A to establish a high voltage circuit for the forward winding of carriage motor 65 and thereby impart forward movement to carriage 24 relative to platform 25. Such forward movement of carriage 24 continues until the operator releases carriage switch C or until the normally closed switch LS6, carried by the side rail 24c of carriage 24 (FIG. 7), engages and is opened by a limiting abutment 252, whichever occurs first. Abutment 25e projects outwardly from the front portion of left-hand side flange 25d of elevator platform 25. It is apparent in FIG. 13 that, upon limit switch LS6 being opened, relay CR7 is deenergized, thereby returning contact sets 7 A, 7C to their normal state and breaking the circuit to forward winding 65' of carriage motor 65 to stop further forward movement of carriage 24.

When carriage 24 occupies a position forwardly of its rearmost position and the operator moves carriage switch C (FIG. 13) downwardly to a lower operative position, current flows through normally closed limit switch LS5, normally closed contact set 7C and relay CR8 to change the stage of contact sets8A-8C. In so doing, normally open contact set 8A is closed and establishes a circuit to reverse winding 65' of carriage motor 65 to thereby impart rearward movement of carriage 24.

Carriage 24 continues to move rearwardly until the operator releases carriage switch C or until normally closed limit switch LS5, which also is carried by side rail 240 (FIG. 7) of carriage 24, engages and is opened by an abutment 25f, whichever occurs first. Abutment 25f projects outwardly from the rear portion of side flange 25d of elevator platform 25. It is apparent that, upon switch LS being opened, relay CR8 is deenergized and contact sets 8A-8C return to their normal state. Thus, winding 65" of carriage motor 65 is deenergized to stop further rearward movement of carriage 24.

It will be noted that the simultaneous energization of both forward and reverse windings of any one of the motors 43, 60, 65 (FIG. 13) is prevented because contact sets 36, 4c, 5c, 6c, 7c and 8c are normally. closed, but are opened when the respective relays CRIS-CR8 are energized. Thus, relays CR4, CR6, CR8 cannot be energized while the respective relays CR3, CR5, CR7 are energized and vice versa.

AUTOMATIC OPERATION OF CHAIR The operation of the treatment chair will now be described for automatically and collectively moving the elevator platform, main carriage, seat rest, back rest and leg rest components between the predetermined treatment" positions of FIG. 2 and the predetermined exit positions of FIG. 1. In this regard, it will be observed in FIG. 2 that the aforementioned components occupysuch positions relative to each other as to locate a patient or other person on the chair in a generally supine position at a predetermined level for being operated upon by an operator, and wherein seat rest 21 is shown disposed on a substantially higher level than that at which a person may comfortably exit from or enter onto seat rest 21. Also, by way of example, with respect to the horizontal plane of platform 25, to back rest 22 is shown positioned at an angle of about l5, and the frame of seatrest 21 and the leg rest 23 are each shown disposed .atan angle of about 7, with seat rest 21 extending upwardly and forwardly at an angle as opposed to the back rest 22 and leg rest 23 which extend downwardly and forwardly at an angle.

The level occupied by the occupant supporting as sembly when the components 21, 22, 23 thereof occupy predetermined treatment positions or exit positions may be varied to suit the operator. For example,

in the treatment" position (FIG. 2), the median center of seat cushion 2111 may be about 25 to inches above the floor, and theexit" position (FIG. 1), the median center of cushion 21h maybe about 17 to 21 inches above the floor. However, by operating elevator switch A (FIG. 13), the occupant supporting assembly may be moved to a lowermost position in which the median center of cushion 21h may be about 12 inches above the floor, or the occupant supporting assembly 20 may be raised to its uppermost position in which the median center of cushion 2112 may belocated about 34 to 36 inches above the floor, for example. 7

When the occupant supporting assembly 20 occupies the exit position of FIG. 1 or a lower position, back rest 22 is substantially erect, to the extent that it extends at an angle of about 70 to 76 relative to the substantially horizontal plane of platform 25 and the frame of seat rest 21. Also, leg rest 23 then occupies an angle of about to 40 with respect to the supporting floor for the chair.

However, the length of leg rest 23 may be such that a slide member 230 on the front lower portion thereof (FIGS. 1 and 2) may engage and slide upon the supporting floor as the occupant supporting assembly 20 approaches the exit" position in the course of downward movement thereof. Thus, the lower portion of leg rest 23 is pivoted forwardly by engagement with the floor so that it swings away from the supporting roller 55d on thrust beam 55 whenever thrust beam 55 occupies its rearmost position and occupant supporting assembly 20 is being moved through about the lower onethird of its range of vertical movement.

As heretofore indicated, the manually operable push button treatment and exit switches D, E are provided for selectively and automatically positioning the components of the occupant supporting assembly 20 in the respective treatment and exit" positions of FIGS. 1 and 2. The automatic or cyclical operation of the chair is such that, during the course of movement of the occupant supporting components 21, 22, 23 between the exit and treatment positions of FIGS. 1 and 2, or anywhere within the range thereof, back rest 22 causes the head rest 52 attached thereto to move in a substantially vertical plane throughout at least the major portion of vertical movement of back rest 22 so that the patients head will always be within about 2 to 3 inches of a given vertical line to maintain the patients head within a convenient working; area or column between narrowly spaced vertically extending limits, as indicated by the arrows H in FIG. 3.

AUTOMATIC TREATMENT CYCLE Assuming, for example, that the components of the chair occupy the exit positions of FIGS. 1 and 10, with all of the individual control switches A-C and the respective abort switches A-C occupying inoperative or open positions, when the operator wishes to automaticallyposition the chair components in the treatment position of FIG. 2, he simply momentarily closes push-button treatment switch D of FIG. 13. In so do ing, current flows through the normally closed contact set 213 and treatment" switch D to energize treatment relay CR1 and change the state of contact sets lA-lE. This closes contact sets 1A, 1B, 1C, 1D and opens contact set 1E.

At this instant, contact set 1C will have no effect on carriage motor 65, but will have a delayed effect thereupon through switch DS3, as will be later described.

The closing of contact set 1A, however, energized elevator relay CR4 through normally closed switches 081, L51 and the normally close-d contact set 3C of relay CR3, thus changing the state of the contact set 4A-4C. This not only completes the circuit to the forward or up" winding of elevator motor 43, but it also establishes a flow of current through thyristor 71, contact sets 48 and 1B, and relay CR1, which current flow then by-passes treatment" switch D so that it may be released by the operator. It should be noted that, as long as any one or more of the normally open contact sets 48, 5B, 8B is in a closed state, upon treatment relay CR1 having been energized previously, treatment relay CR1 will remain energized.

, Since thrust beam 55 occupies a rearward position when the components of the chair occupy the exit positions of FIGS. 1 and 10, it follows that limit switch LS4 (FIGS. 7, 13 and 14) is closed. Also, while in the exit" position, thrust beam 55 occupies a rearward position relative to carriages 24, 50 (as in FIG. 14) so that switch 083 also is closed, as will be later explained (FIGS. l4, l5 and 16). Consequently, when treatment switch D was momentarily closed, current was also caused to flow through contact sets 1D, 6C (FIG.

13) and switches S3, LS4 to energize relay CR and change the state of contact sets 5A-5C. Contact set 5A then effects energization of forward winding 60 of tilt motor 60 so that thrust beam 55 starts to move forwardly to tilt the occupant supporting components 21, 22, 23 toward the treatment position of FIG. 2 as elevator platform 25 starts to move upwardly.

When elevator platform 25 has moved upwardly to the predetermined treatment level of FIG. 2, the high surface of a vertically movable, stepped slide cam 72 (FIGS. 4, 13 and 17) moves into engagement with and opens switch 081 (FIGS. and 13) while permitting normally open switch 052 to remain open. Thus, the opening of switch 081 breaks the circuit to relay CR4, thereby opening contact set 4A and stopping motor 43. It should be noted that, if elevator platform 25 was higher than the predetermined treatment level when treatment switch D was closed, the high surface of slide cam 72 would have been in registration with switches O81, OS2 and they would have been open and closed, respectively.

Consequently, current then would have flowed through relay contact sets lA, 4C and switches 0S2, LS2 to energize relay CR3 instead of relay CR4. As described earlier, energization of relay CR3 effects energization of reverse winding 43" of elevator motor 43, causing platform 25 to move downwardly. Such downward movement would continue until slide cam 72 again causes both switches O81, 082 to be open. Since both switches O81, 052 are then open, platform 25 will not be moved further upwardly or downwardly unless the operator closes manual elevator switch A or exit switch E.

It will be observed in FIGS. 4 and 17 that switches O51, 082 are mounted on an arm 72a guided for vertical adjustment-in a bracket 7212 on the left-hand side of the depending rear portions 25 of elevator platform 25. Arm 72a is threadedly penetrated by an adjustment screw 72c extending through platform 25. Slide cam 72 also is guided for vertical movement in bracket 72b and has a link 72d extending upwardly therefrom and connected to the adjacent uppermost parallelogram link 34a. Thus, it is apparent that slide cam 72 moves downwardly relative to elevator platform 25 during upward movement of platform 25, and that slide cam 72 moves upwardly relative to platform 25 during downward movement of platform 25.

The switches DSl, DS2 also are controlled by a stepped slide cam 73. As shown in FIGS. 4, l0, l8 and 19, switches DSl, DS2 are secured for vertical adjustment to a bracket 73a suitably secured to the righthand side (FIG. 4) of the depending rear portions 25' of elevator platform 25. Slide cam 73 is mounted for vertical sliding movement in bracket 73a and has a link 73b extending therefrom and connecting the same to the upper right-hand parallelogram link 34. Thus, upward and downward movement is imparted to both slide cams 72, 73 relative to and during respective downward and upward movements of elevator platform 25. However, since contact set 2A is open during the treatment cycle operation; i.e., during movement of the occupant supporting components to the treatment position of FIG. 2, the state of switches DSl, DS2.has no effect on the operation of the chair during the treatment cycle.

The normally closed switch DS3 is held in open position during automatic operation by engagement thereof with the upper surface of left-hand side bar 55b of thrust beam 55 (FIG. 14) substantially throughout the vertical movement of platform 25 between the exit and treatment levels indicated in FIGS. 1 and 2. However, at about the time that elevator platform 25 reaches the treatment" level during the course of upward movement thereof in a treatment" cycle, a longitudinally extending groove or recess 55m (FIG. 14), in the forwardly moving left-hand side bar 55b of thrust beam 55, moves into registration with switch DS3, permitting the same to close. Since normally open contact set 1C, in the lower left-hand portion of FIG. 13, was closed when treatment relay CR1 was energized, current then flows through switches DS3, LS6, and contact sets IC, SC to energize relay CR7 and thus establish a circuit to the forward winding 65 of carriage motor 65 in the manner heretofore described.

Thus, although upward movement of elevator platform 25 may have ceased, main carriage 24 then moves forwardly at the same time that thrust beam 55 is moving forwardly relative to main carriage 24. Carriage 24 continues to move forwardly until either the recess 55m (FIG. 14) moves out of registration with switch D53 and the upper surface of side bar 55b then opens switch DS3, or limit switch LS6 moves into engagement with and is opened by abutment 25e (FIGS. 7 and 13), whichever occurs first.

Switch DS3 may be mounted on bracket 21k (FIGS. 7 and 14) so that it may be adjusted longitudinally of thrust beam 55 and so that switch DS3 will be opened either before or simultaneously with the opening of limit switch LS6 when it engages abutment 25e. However, forward movement of thrust beam 55 relative to carriages 24, may cease before, after or at the same time as forward movement of carriages 24, 50 ceases during automatic operation.

If main carriage 24 is still moving forwardly at the time that thrust beam ceases forward movement relative to main carriage 24, it is apparent that thrust beam 55 then will continue to move forwardly in fixed relation to main carriage 24. During automatic operation to the treatment position, it is preferred that the groove 55m (FIG. 14) in bar 55b of thrust beam 55 moves forwardly out of registration with switch DS3 at the instant that forward movement of main carriage 24 ceases. However, before thrust beam 55 reaches its forwardmost position relative to main carriage 24 and bracket 21k (FIGS. 14 and 15), a ramp cam 55n on bar 55b engages and opens normally closed switch DS4. This insures that, when the exit switch E is closed thereafter, the main carriage 24 and the occupant supporting assembly 20 will not start to move rearwardly-relative to elevator platform 25 before thrust beam 55 starts to move rearwardly relative to carriage 24. This is desirable so that the patient's head can be maintained within the aforementioned convenient working area between narrowly spaced vertically extending limits.

As shown in FIGS. l4, l5 and 16, the right-hand side bar 55a of thrust beam 55 has a longitudinally adjustable abutment 55p thereon for adjustably limiting the extent to which thrust beam 55 may be moved forwardly relative to carriages 24, 50 and seat rest 21 during automatic operation to treatment position. Abutment 55p opens and closes switch 083 through a toggle-action cam 55q pivoted on bracket 21k. Cam 55q is rotated counterclockwise (FIG. 16) by abutment 55q as thrust beam 55 moves rearwardly relative to bracket 21k, thus permitting switch 053 to close. Cam 55q is rotated clockwise from the position of FIG. to that of FIG. 16 each time abutment 55;) moves forwardly against and past cam 55: thus opening the normally closed switch 053. Of course, the maximum extent to which thrust beam 55 may be moved under control of individual tilt switchA (FIG. 13) in the forward and rearward directions relative to carriages 24, 50 is determined by abutments 55j, 55k and the respective limit switches LS4, LS3 (FIG. 14).

It is thus seen that, during automatic treatment" operation of the chair, regardless of whether or not the main carriage 24 has ceased its forward movement, when the adjustable abutment 55p in thrust beam 55 moves forwardly into engagement with'toggle cam 55: and opens switch 083, if abutment 55j has not already opened limit switch LS4, switch 083 breaks the circuit to recline relay CR5 to change the state of contact sets 5A-5C arid break the circuit to tilt motor 60. All of the contact sets 38, 4B, 6B, 88 now already occupy open position, since relay CR5 is the last of the motoroperating relays to be energized during the automatic treatment cycle of the chair. It follows therefore that contact set 58 is opened with deenergization of relay CR5 and, thus, treatment relay CR1 is deenergized to complete the treatment cycle of the chair.

The toggle cam 55q is provided to insure that switch 053 is held open even though abutment 55p may be caused to move forwardly after it has initially opened switch 033 upon the completion of a treatment cycle due to an operator moving the switch B upwardly in FIG. 13. This is a precautionary measure in the event that a persons arm may be positioned between back rest 22 and platform when they occupy the relative positions shown in FIG. 2 and an operator might then accidentally close the tieatment switch D. In other words, the closing of treatment switch D under such condition cannot effect energization of relay CR5 and motor winding 60, it then being necessary to first operate either the exit' switch E or switch 8 to move abutmerit 55p rearwardly pasttoggle cam 55q before treatment" switch D can be effective to energize relay CR5 and motor winding 60.

It is important to note that, if the operator intentionally or unintentionally moves any one or more of the individual control switches A-C to either of its respective operative positions during automatic treatment" or exit cycles of the chair, the corresponding abort switch A, B or C, as the case may be, will also be moved to an operative or closed position to prevent thyristor 71 from conducting and thereby to interrupt the flow of current to whichever of the relays CR1 or CR2 may have been energized previously, even though one or more of the contact sets 38, 4B, 5B, 6B, 88 may be closed. In other words. during the course of either an automatic treatment? cycle or an automatic exit cycle in the operation of the chair, the instant that any one of the abort switches A, B, C is moved with a respective one of the switches A, B, C to closed position, it will stop such automatic cycle in the operation of the chair and individual operation of the motors 43, 60, 65 then may be effected by manual manipulation of the respective switches A-C, in the manner heretofore described. I

AUTOMATIC EXIT CYCLE Assuming that the components of the chair occupy the treatment positions of FIG, 2, in order to effect an automatic exit cycle in the operation of the chair, the operator need only momentarily close the exit switch E to energize exit relay CR2 through contact set 1E. Since this closes contact sets 2A, 2B, 2C, 2D current then flows through contact sets 2D, 5C and limit switch LS3 to energize relay CR6 and complete a circuit to the reverse winding of tilt motor 60 in the manner heretofore described. At the same time, relay CR6 closes contact set 6B to complete a circuit through thyristor 71 and contact set 28 to exit relay CR2, by-passing exit switch E, which then may be released.

Of course, upon energization of reverse winding 60" of tilt motor 60, thrust beam 55 starts to move rearwardly, from right to left in FIG. 7, relative to carriages 24, 50. Also, since the respective normally closed and normally open switches DS1, DS2 (FIGS. 4, l3, l7 and 18) are being held in respective open and closed positions by the high surfaces of slide cam 73 when the elevator platform 25 occupies treatment level, energization of exit relay CR2 also caused current to flow through contact sets 2A, 4C and switches DS2, LS2 to energize relay CR3 and thereby establish a circuit to reverse winding 43" of elevator motor 43 in the manner heretofore described.

Upon occurrence of sufficient rearward movement of thrust beam 55 to move ramp cam 5511 out of registration with switch DS4, permitting the same to close, current then flows through switches D34, LS5 and contact sets 2C, 7C to energize relay CR8 and thus close a circuit to reverse winding of carriage motor 65 in the manner heretofore described. Thus, carriages 24, 50 and seat rest 21 move rearwardly as thrust beam 55 moves rearwardly relative to carriage 24 and as elevator platform 25 moves downwardly. By delaying rearward movement of carriages 24, 50 and seat rest 21 until ramp cam 55n has moved out of engagement with switch D84, this ensures that the free rear edge of back rest 22 will move upwardly in the desired operating work column rather than moving rearwardly relative to the elevator platform 25.

Rearward movement of thrust beam 55 relative to carriages 24, 50 continues until abutment 55k thereon (FIGS. 13 and 14) engages and opens limit switch LS3, at which instant back rest 22 occupies the erect position shown in FIGS.,1 and 10. Also, rearward movement of carriages 24, 50 relative to elevator platform 25 continues after groove 55m, in left-hand side bar 55b of thrust beam 55, moves out of registration with switch DS3 so that the upper surface of bar 55b opens normallyclosed switch DS3 at substantially the same time as or before limit switch LS5 moves into engagement with and is opened by abutment 25f FIGS. 7 and 13).

It is apparent that the opening of switch DS3 at this time simply conditions the same for the next treatment" cycle. The opening of switch LS5, however, de energizes relay CR8 to stop carriage motor 65, with carriages 24, 50 than occupying their rearmost positions as shown in FIGS. 1 and 10. The downward movement of elevator platform 25 also continues during the automatic exit cycle of the chair until slide cam 73 has moved upwardly relative to platform 25 sufficiently to move the low surface thereof into registration with switch D52 (FIGS. l3, l8 and 19) to break the circuit to relay CR3, thus breaking the circuit to elevator 

1. A movable, power operated treatment chair for supporting a patient in selected various positions therein and characterized by being selectively individually or collectively movable in vertical, horizontal or tilting directions; said chair comprising a stationary base means for supporting said chair; platform means connected with and supportEd by said base means for vertical, up and down movement with respect thereto; carriage means operatively connected with and supported by said platform means for vertical movement therewith and for horizontal, back and forth movement with respect thereto; patient supporting means operatively connected with and supported by said carriage means for horizontal and vertical movement therewith and for back and forth tilting movement with respect thereto and including a seat rest component, a back rest component pivotally connected to said seat rest, and a leg rest component pivotally connected to said seat rest for tilting movement of each component with respect to the other said components; tilting means connected with said carriage means and said patient supporting components for causing tilting movement of said components with respect to each other and with respect to said carriage means; selectively actuatable power means connected with said platform means, said carriage means and said tilting means for movement thereof; and selectively operable control means connected with said power means for selectively individually and independently actuating said power means to move said patient supporting means vertically, horizontally or tilting said patient supporting components with respect to each other to desired positions without requiring the other movements and for actuating said power means to collectively and simultaneously move said patient supporting means through a predetermined portion of these movements to predetermined exit and treatment positions, said control means including abort means operable for deactuating said power means to stop the collective and simultaneous movements when said control means is operated to effect an individual movement, in which said control means include a manually operable, normally inactive switch means, and circuit means operatively connected between said power means and said switch means and responsive to activation of said switch means for actuating said power means in predetermined relation to each other.
 2. A treatment chair, according to claim 1, wherein said power means comprises a reversible platform electric motor operatively connected with said platform means for effecting the vertical movement thereof, a reversible carriage electric motor operatively connected with said carriage means for effecting the horizontal movement thereof, and a reversible tilting means electric motor operatively connected with said tilting means for effecting the tilting movement thereof.
 3. A treatment chair, according to claim 2, in which said control means include a manually operable, normally inactive treatment switch, and electric circuit means operatively connected between said electric motors and said switch and responsive to activation of said treatment switch for actuating said motors in predetermined relation to each other for collectively moving said carriage means, said platform means and said tilting means for moving said patient supporting components to a predetermined treatment position in which said back rest is in a nearly horizontal position, said carriage means and patient supporting means are in a predetermined forward position relative to said platform means and said platform means and said patient supporting means are positioned at a predetermined relatively high treatment level, in the event that said patient supporting components do not already occupy said predetermined treatment position.
 4. A treatment chair, according to claim 3, in which said control means further includes three individual normally inactive, manually operable switches and associated electrical circuit means, said three switches being connected in parallel to said respective motors for operating the same independently of each other, and said abort means being responsive to activating any one of said individual switches for interrupting operation of said circuit means responsive to activation of said treatment switch if sAid last-named circuit means is then in operation.
 5. A treatment chair, according to claim 2, in which said control means include a manually operable, normally inactive exit switch, and electric circuit means operatively connected between said electric motors and said switch and responsive to activation of said exit switch for actuating said motors in predetermined relation to each other for collectively moving said carriage means, said platform means and said tilting means for moving said patient supporting components to a predetermined exit position in which said back rest occupies an erect nearly vertical position, said carriage means and said patient supporting means occupy a predetermined rearward position with respect to said platform means, and said platform means and said patient supporting means occupies a predetermined relatively low exit level, in the event that said patient supporting components do not already occupy said predetermined exit position.
 6. A treatment chair, according to claim 5, in which said control means further includes three individual normally inactive, manually operable switches and associated electrical circuit means, said three switches being connected in parallel to said respective motors for operating the same independently of each other, and said abort means being responsive to activating any one of said individual switches for interrupting operation of said circuit means responsive to activation of said exit switch if said last-named circuit means is then in operation.
 7. A treatment chair, according to claim 2, in which said control means includes a manually operable, normally inactive, two way, horizontal movement switch means, and electric circuit means operatively connected between said carriage electric motor and said switch means and responsive to activation of said switch means in one direction for actuating said carriage motor for moving said carriage means and said patient supporting means forwardly and being responsive to actuation of said switch means in the other direction for moving said carriage means and said patient supporting means rearwardly, and limiting means operatively associated with said carriage means and responsive to forward and rearward movement of said carriage means to respective predetermined forward and rearward positions for stopping said carriage motor means in the event of said manually operable horizontal movement switch means then being actuated.
 8. A treatment chair, according to claim 2, in which said control means includes a manually operable, normally inactive, two way, vertical movement switch means, and electric circuit means operatively connected between said platform electric motor and said switch means and responsive to activation of said switch means in one direction for actuating said platform electric motor for moving said platform and said patient supporting means upwardly and being responsive to actuation of said switch means in the other direction for moving said platform means and said patient supporting means downwardly, and limiting means operatively associated with said platform means and responsive to upward and downward movement of said platform means to respective predetermined upward and downward positions for stopping said platform motor means in the event of said manually operable vertical movement switch means then being activated.
 9. A treatment chair, according to claim 2, in which said control means includes a manually operable, normally inactive, two way, tilt movement switch means, and electric circuit means operatively connected between said tilting means electric motor and said switch means and responsive to activation of said switch means in one direction for activating said tilting means motor for causing tilting movement of said patient supporting components in one direction and being responsive to activation of said switch means in the other direction for tilting said patient supporting means in the other direction, and limiting means operatively aSsociated with said tilting means and responsive to tilting movement of said patient supporting means in respective predetermined tilting positions in each direction for stopping said tilting means motor in the event of said manually operable tilting movement switch means then being activated.
 10. A treatment chair, according to claim 2, in which said tilting means includes thrust means guidingly carried by said carriage means for forward and rearward movement relative to said carriage means and including means drivingly connecting said thrust means to said tilting means motor for moving said thrust means by said tilting means motor forwardly and rearwardly alternatively, means connecting said back rest to said thrust means for changing the angular position of said back rest with respect to said seat rest upon movement of said thrust means, means operatively associated with said seat rest and said thrust means for changing the angular position of said seat rest relative to said carriage means upon movement of said thrust means, and means forming part of said thrust means and engagable with a medial portion of said leg rest means for causing said leg rest means to tilt upwardly and downwardly relative to said seat rest means during respective forward and rearward movements of said thrust means.
 11. A treatment chair according to claim 10 wherein said carriage means comprises a main carriage guided for forward and rearward movements on said platform means, an auxiliary carriage on which said seat rest is secured, means pivotally mounting said auxiliary carriage to said main carriage on a lateral axis adjacent the rear portion of said main carriage, ramp means carried by said main carriage and inclined upwardly and forwardly at an angle with respect to said main carriage, and follower means on said thrust means enegaging said ramp means whereby, during forward and rearward movements of said thrust means relative to said carriage means, the front portion of said thrust means is moved upwardly and downwardly, respectively, about said lateral axis to impart corresponding movement to said auxiliary carriage and said seat rest relative to said main carriage while pivoting said back rest relative to said seat rest.
 12. A treatment chair, according to claim 2, in which said platform means includes a parallelogram linkage means interposed between and interconnecting said platform means and said base means, and in which said platform motor means is operatively connected to said parallelogram linkage for expanding and contracting said parallelogram linkage to raise and lower, respectively, said platform means relative to said base means. 